1. Field
The present disclosure is generally related to bridge upgrades and replacement, and in particular to replacement of a bridge cap without or prior to alteration or replacement of a bridge deck.
2. Description of Related Art
It may be desirable to repair or replace a bridge without rerouting the traffic that frequently traverses it. For example, railroad bridges typically carry regular freight or passenger traffic which cannot be easily or cheaply rerouted. As such, repair or replacement of such bridges is preferably conducted in a manner that would have minimal disruption to the bridge deck. For example, by installing new columns and bridge caps adjacent to old (i.e. preexisting) columns and bridge caps, the old columns and bridge caps may become redundant to supporting the bridge deck and beams, and may subsequently be removed. Alternatively, the columns and/or caps may be replaced individually, one at a time. Throughout this process, traffic may traverse the bridge deck unimpeded. Once an entire set of new columns and bridge caps are in place, the bridge deck and the support beams may be quickly replaced.
Conventionally, the process of replacing a bridge cap without disturbing the bridge deck and beams is a multi-step process, requiring repeated engagements between a lifting apparatus and the bridge cap that is being lifted into place. For example, in some conventional configurations, such as that described in U.S. Pat. No. 7,363,671, the lifting apparatus may need to be repeatedly adjusted as the bridge cap is slid between the beams and the new columns. For example, in that configuration, multiple lift rods are configured to selectively engage or disengage the bridge cap, by extending through the bridge deck in spacings between the bridge beams. The bridge cap is then slid until an engaging one of the lift rods moves adjacent to one of the bridge beams, at which time a disengaged lift rod is moved through a different spacing between the bridge beams to assist in supporting the bridge cap, while the lift rod that is adjacent to the bridge beam is disengaged. The sliding movement of the bridge cap then may continue, with the repeated engagement and disengagement of the lift rods between the bridge beams, until the bridge cap is supported on both sides of the bridge beams and bridge deck, to lift the bridge cap into final position on the columns.
It may be appreciated that each engagement and disengagement of the bridge cap (i.e. through the lift rods extending between the bridge beams and bridge deck) is potentially hazardous to field personnel and other workers assisting the lift, as they must be in close proximity to the lifted bridge cap to position and engage the lift rods, or other support structures. Additionally, the bridge deck must often be modified so as to expose the spacing between the bridge beams, to allow for the progressive and gradual movement of the new bridge cap onto the associated columns. Furthermore, with each engagement between spaces of the bridge beams, a potential of accidently impacting the bridge beam is increased.